{{ if .Params.updated }}
  {{ .Scratch.Set "lastUpdated" .Params.updated }}
{{ else }}
  {{ .Scratch.Set "lastUpdated" .Date }}
{{ end }}

<time class="article-date" itemprop="dateModified" datetime="{{ dateFormat "2006-01-02" (.Scratch.Get "lastUpdated") }}">
  {{ dateFormat "Jan 2, 2006" .Date }}
  {{ if .Params.updated }}
    • Updated: {{ dateFormat "Jan 2, 2006" .Params.updated }}
  {{ end }}
</time>